The optical fibers used in signal transmission is an emerging application further to the electric cable. Nowadays, with the advantage of high transmission efficiency, the optical fiber has played a decisive role in modern technology. The optical fiber used in signal transmission is to carry or transmit energy for applying to industrial purposes, such as welding, laser cutting or other precision machining operations.
The carrying load of energy of high-power optical fibers is distinctly higher than general uses. Therefore, such high-power optical fibers must be equipped with an external heat dissipation mechanism, otherwise the high temperatures will cause other components failure and even the damage to the system.
To dissipate the heat of the high-power optical fibers, a package structure of the optical fiber in prior art was provided. In the package structure, the optical fiber is surrounded by the substrate with high thermal conductivity, and the optical fiber is connected with the substrate by two ends to ensure the heat exchange with the substrate. However, since the low conductivity of heat of the adhesive, the heat exchange between the optical fiber and the substrate is inefficient. This disadvantage results in the thermal stress and therefore the breakage of the package structure. Furthermore, to avoid the issue caused by the different coefficients of thermal expansion, the material of each component, and the bonding length of the substrate and the optical fiber are also constrained. Consequently, the package structure in prior art is not conducive to design and with high risk of failure.
Another prior art is to replace the aforementioned package structure with a cavity coated with a power dissipative material (such as a UV-cured low refractive index polymer or an epoxy resin), and bond the optical fiber with high refractive index epoxy resin at both ends of the package structure. The coating material in the cavity will limit the applicable field of the optical fiber. Moreover, in particular parts the optical fiber is temperature sensitive and therefore inappropriate for bonding, this leads the adhesives and these parts of the optical fiber must be staggered in position when bonding so makes the package structure longer.